Autism Begins in Pregnancy, Study Says

(HealthDay News) — Most young children with autism have focal disruption of cortical laminar architecture, according to a study published in the March 27 issue of the New England Journal of Medicine.

Rich Stoner, PhD, from the University of California in San Diego, and colleagues used RNA in situ hybridization with a panel of layer- and cell-type-specific molecular markers to examine neocortical architecture during the early years after autism onset. Markers for neurons and glia were assayed, as well as genes that have been implicated in the risk of autism, in tissue from post-mortem samples obtained from children with autism and unaffected children aged 2–15 years.

In 10 of 11 children with autism and one of 11 unaffected children, the researchers observed focal patches of abnormal laminar cytoarchitecture and cortical disorganization in neurons, but not glia, of prefrontal and temporal cortical tissue. With respect to cell types that were most abnormal in the patches and layers that were most affected by pathological features, there was heterogeneity between cases. The clearest signs of abnormal expression were in cortical layers 4 and 5, but no cortical layer was uniformly spared. The focal geometry and size of patches were confirmed on three-dimensional reconstruction of layer markers.

"Our data support a probable dysregulation of layer formation and layer-specific neuronal differentiation at prenatal developmental stages," the authors write.